Budgets and money and savings OH MY!

So I'm really good at making budgets. REALLY good at it. I am not, however, so good at actually keeping to them which means that my efforts in budget making quickly fall by the way side and I'm left with no money at all and a week to go before pay day.
I make, roughly 1400 a month and spend roughly 1100. That's rent, car payments, loan payments, gas, (a very generous allowance for) food, entertainment and bills. But the other three hundred just seems to disappear every month. I know where it goes (hello coffee shops, cigarettes and fast food) but I'm amazed that there's so much of it gone.
What do you do to keep from spending the extra money every month? How do you force yourself to save those pennies?
I'd like to move but to do that I need to get a deposit together. Saving $300(+) a month would mean that I could be out within three months but every month my savings account continues to collect dust. Help!